The objective of this research is to deduce the detailed mechanism for respiratory chain linked oxidative phosphorylation. The transport of electrons to oxygen through the respiratory chain is coupled with the synthesis of adenosine triphosphate. The hypothesis is that a chemically identifiable high energy intermediate is formed in the primary energy conserving process. A series of physical organic, electrochemical, and spectroscopic techniques will be used to investigate this high energy intermediate. Electrochemical methods appear to be the most suitable for generating highly reactive intermediates free from contaminants. The structures of the intermediates will be determined spectroscopically (ir, uv, and epr). The techniques of physical organic chemistry will be used to study the reactions of these intermediates. Particular attention is being paid to the possible intermediacy of electron deficient sulfur species. The generation of such entities and their ability to effect phosphorylation of nucleotides by inorganic orthophosphate is being investigated.